What is the primary goal of a firewall in a network security architecture?

The primary goal of a firewall in network security architecture is to filter incoming and outgoing traffic based on predefined security rules. Firewalls serve as a critical barrier between trusted internal networks and untrusted external networks, such as the internet. By implementing a set of rules, firewalls can allow or deny specific traffic based on factors like IP addresses, port numbers, and protocols, effectively controlling the flow of data into and out of the network.

This function is essential for protecting the network from unauthorized access, potential breaches, and various types of cyber threats. By analyzing data packets, firewalls can help identify suspicious activity and respond accordingly, ensuring that only legitimate traffic is allowed through.

The other options describe functions that do not align with the core purpose of a firewall. While encryption of data packets is crucial for securing data, it is not a role performed by firewalls. Similarly, preventing physical access to servers pertains to physical security controls, not network security. Monitoring user behavior is typically the domain of security information and event management (SIEM) solutions or user behavior analytics tools rather than firewalls, which focus on traffic filtering. Thus, filtering traffic based on security rules remains the defining characteristic of a firewall's function in network security.